1. Field of the Invention
This invention relates to a humidity measurement device in which humidity in an atmosphere is measured by using an electrochemical cell.
2. Description of the Prior Art
In a humidity measurement device of this type, there have been devices known in Japanese Provisional Publication Patent Nos. 60-222761, 62-150151 and 62-150152.
In the Japanese Provisional Publication Patent No. 60-222761, partial pressure of oxygen component in a gas is measured with the function of limit currents, each value of which is obtained before and after removing aqueous vapor component from the gas.
The Japanese Provisional Publication Patent No. 62-150151 teaches that the limit currents due to gas diffusion are obtained depending on an oxygen density and an aqueous density in the gas. The difference between values of the limit currents leads to humidity measurement.
Further, the Japanese Provisional Publication Patent No. 62-150152 suggests that a first limit current due to the oxygen density and a second limit current due to the aqueous density are obtained. Then a third limit current based on a dehumidified gas is obtained The humidity is measured based on the difference between the third limit current and at least one of the first and second limit currents.
In each device according to the Japanese Provisional Publication Patent Nos. 60-222761, 62-150151 and 62-150152, however, a dryer device is required to desiccate so as to remove aqueous vapor from the gas atmosphere, simultaneously a measurement device is required to measure the limit current. Thus necessitates a large scale measurement system as a whole resulting in a slow operation of the humidity measurement.
Therefore, the invention has its object to provide a humidity measurement device which is capable of eliminating all the drawbacks mentioned above.
It is an object of the invention to provide a humidity measurement device which is capable of measuring humidity level with a high accuracy.
It is an object of the invention to provide a compact humidity measurement device which is capable of measuring humidity with a quick response.